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Measured impacts of supermarket humidity level on defrost performance and refrigerating system energy use.

Author(s) : HENDERSON H. I., KHATTAR M.

Summary

The paper presents field-monitored data from two supermarkets (A and B) where the impact of space humidity on refrigerating system energy use was evaluated. The results at store B showed that refrigerating system energy use decreases by nearly 10 kWh/day for each 1% drop in space relative humidity, or about 0.4% of average annual system energy use. At store A, the measured data show that implementing temperature-terminated defrost reduced refrigerating system energy use by nearly 70 kWh/day over the winter period when the average space humidity was 22% relative humidity. The savings from temperature-terminated defrost increase by 4 kWh/day per each 1% drop in relative humidity. At both stores, the same type of mechanical controls were used to duty cycle the anti-sweat heaters based on store dew point. Anti-sweat heater electricity use was observed to decrease by 4.6 kWh/day at store B and 3.4 kWh/day at store A for each 1% drop in relative humidity. The overall energy reduction factor at the two stores was 12 kWh/day per % relative humidity at store A and 15 kWh/day per % relative humidity at store B. With more aggressive anti-sweat heater control, reduction factors as high as 20 kWh/day per % relative humidity appear to be possible.

Details

  • Original title: Measured impacts of supermarket humidity level on defrost performance and refrigerating system energy use.
  • Record ID : 2000-1865
  • Languages: English
  • Source: ASHRAE Transactions. 1999 Winter Meeting, Chicago, Illinois + CD-ROM.
  • Publication date: 1999
  • Document available for consultation in the library of the IIR headquarters only.

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